We use a process called stabilization.
Stabilization is a special treatment to increase the strength and durability of the wood.
It is a process where the wood is completely immersed in a sap that acts as an impregnating agent, then everything is placed inside a vacuum chamber capable of reaching high pressures.
This process causes the air to exit the pores, allowing the sap to penetrate deep into the fibers, wrapping them; once dry, the wood becomes significantly stronger and more durable.